Drawing press



0. KUHNER DRAWING PRESS May 10, 1932.

Filed March 31. 1930 k I r a ir 0 ill n v a FWJ H w i H r a a fl a n w M H F 27 f 6 n I a 1 1| G H IIIIIM n x V J r S 2 05:0 Ka finer 2 holder;

Patented May 10, 1932 stars FATE one "or eoififinenn, arment, ass gaea re Shannan A.-e., 6r? eo'r'rmenn, GERMANY, A comes-Arron DRAWING rnnss Application filed-March 31-, 1930, Serial No. 440,52"), and in Germany April 12',--19?a'9;

piston, the second piston in turn supporting the inner annular blank holder. The dra-wing matrix as the ram descends and at first acts on the outer blank holder through the 35 blank while the inner blank holder acts as .the drawing punch, andthe blank is cupped on the inner blank holder until a shoulder in the cavity of thematrix bears on the fiange of the partly formed cup and the inner blank The inner blank holder surrounds a fixed drawing punch which performs the final cupping operation.

In this system during the first stage of the pneumatic pressure which is much 1n excess of that required for the second stage so that for the second stage the compressed air supporting the inner'annular blank holder must so be partly discharged before the second stage is started, involving considerable loss of energy. V

It is an object of my invention to eliminate this drawback. To this end I provide multiple means for supporting the inner annular blank holder and means 'operati'vely connected with the outer annular blank holder for partly cutting out such multiple supporting means at the end of the first stage.

In this manner the inner annular support is under sufiicient pressure for the first stage while during the second stage the pressure is only that required for supporting the blank in such manner as to eliminate theformation of cracks in the blank.

In reducing my invention to practice I .may provide three pneumatic pistons, one supporting the outer blank holder, and the other'supporting the innerblank holder, while the third piston'provides an additional Fig. 1 is an axial section of the operation the inner annular blank holder ton pressand the lower part of the rain with '25 which acts as the. drawing punch requires a In a modification of my invention I'pro .vide two pistons only, one for the outer and one-for the inner blank holder, insert a spring between the inner blank holder and its piston, and provide means for operating I the spring together'with the pistondur'ing the first stage, and alone during the second stage, after its supportingpiston has been positively engaged by the ram, as described with reference to the type with three piston-s. In the drawings. affixed to this specification and forming part'thereof alpress having three pistons, and a press having two pistons and a spring, are illustrated :di'a'gr'aminatically byway of example.

In the drawings jthree-pisthe matrix, and i .1 r

Fig. 2 is an. axial section of the'two piston press, the ram and the matrix being omitted.

the support 2, 0 iszt-he inner,2:cZ-is' the outer annular blank holder, w is the fi xed blank ing ring which is secured in the support 2,

11 is a cylinder which is held below the table b by any number of screws 15', only one of which is shown, f, f and a", r, respectively, are pushv bars extending downwardly from the inner and outer bl'ank holders c and d, respectively, and t is ana'nnular slide which is secured on the ends of the rods 1",?" by, nuts 8,8. I r p a Referring now to Fig-:1, 7 is the minor the press, 6 is a matrix which is secured at the lower end of the ram, 9 is a recess e'iitending. inwardly from the lower face of. the ram,- y is a shoulder at the end 'of therecess, and 10 is a spring-controlled piston which is inserted in the matrix so as noriinally to project slightly beyond thefsh'ciul- 13 and 14, respectively, for connecting each chamber with an air vessel, not shown.

it is the rod of the lowermost piston n which projects upwards through the three compartments of the cylinder 11 and is provided with a washer g at its upper end on whiclrt he'rods f of the inner blank holder 0 are abutted.

0 is the hollow piston rod of the second piston p which extends through the partition 7 between the chambers 71 and 7c and is fitted to slide in the uppermost piston g. o is a sleeve which is threaded on the upper end of the hollow piston rod 0 and is provided with a flange u at its lower end. The ring t to which the rods 1" from the outer blank holder cl are secured by the nuts sis fitted to slide on the sleeve 1) and to cooperate with its flange. 10. The lower ends of the rods 7" extend beyond the ring if and the flange u and are supported on the uppermost piston q when the parts are in the initial position illustrated in Fig. 1. V

In operation, when the ram descends it bears on the blank which is supposed to be supported on the blanking ring a: with its lower face w and depresses the inner blank holder cl while separating the blank at w. The uppermost piston g descends with the blank holder d under the action of the rods 7' while air from the compartment i is forced back into the air vessel (not shown) through the pipe 12. The inner blank holder is supported by the pistons p and n until the ring tat thelend of the rods r engages the flange u at the lower end of the sleevem. Consequently, the inner blank holder 0 acts as the drawingpunch for the cup which is formed in the blank during the first stage. The first stage is completed when the ring t engages thefiange u of the sleeve o and moves downwardly the piston p through the medium of its hollow. rod 0 on which the sleeve is secured. The rod 0 now releases the washer g at the lower end of rods f so that the inner blank holder 0 is only supported by the rod h of the lowermost piston n and moves down with the shoulder 3 of the matrix 6 while at the same time the piston n recedes into its cylinder. The second stage is now performed by cupping the blank on the fixed drawing punch a. During the descent of the pistons p and n the air from the respective compartments is and m is expelled through the pipes '13 and 14., respectively, into the air vessel (not shown).

When the ram 7 is reversed the compressed .air from the air vessel flows back into the several compartments, of the cylinder 11 and returns the pistons and the blank holders 0, (Z

on the end of the solid rod h of the lowermost piston n. z is a cross head which is held between the rods f by suitable nuts 2 and F is a spring which is inserted between the cross head a and the the washer g at the end of the rod h. The rods 7 in this instance are free to move independently of the washer g. The ring 6 and the lower ends of the rods 7", and the flange a at the lower end of the sleeve 0) are provided as described. 7 During the first stage only the upper piston g is lowered by the rods 1" of the outer blank holder d while the inner blank holder 0 is retained by the piston n and acts as the drawing punch for the blank during the first stage.. At the end of the first stage the ring 15 engages the "flange u on the sleeve '0 and moves down the piston n so that the second stage is performed only against the pressure of the spring F the initial pressure of which is adjusted by the nuts .2 on therods The several adjusting facilities afforded by displacing the nuts 8, z, and the sleeve 4), serve for adapting the press to various conditions of operation, such as variations in the thickness of the blank and depth of cupping.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

In the claims afiixed to this specification no selection of any particular modification of the invention is intended to the exclusion of other modifications thereof and the right to subsequently make claim to any modification not covered by these claims is expressly reserved.

I claim 1. A drawing press comprising a table, an outer annular blank holder and an inner annular blank holder, both fitted to slide with respect to said table, a fixed drawing punch on said table, a matrix adapted to cooperate with said holders and said punch, a cylinder isposed in a fixed position with respect to said table and having two compartments, a piston mounted to slide in the first compartment, a piston rod on said piston, means operatively connecting said piston rod to said inner blank holder, a piston mounted to slide in the second compartment and on said piston rod, and means operatively connecting said piston in the second compartment to said outer blank holder.

2. A drawing press comprising a table, an outer annular blank holder and an inner annular blank holder, both fitted to slide with respect to said'table, a fixed drawing punch on said table, a matrix adapted to cooperate with said holders and said punch, a cylinder disposed in a fixed position with respect to said table and having three compartments, a first piston mounted to slide in the first compartment, a piston rod on said piston, means operatively connecting said piston rod to said inner blank holder, a second piston mounted to slide in the second compartment, a hollow piston rod on said second piston which is mounted to slide on the piston rod of said first piston, a third piston arranged in the third compartment and mounted to slide on said hollow piston rod, means operatively connecting said third piston to said outer blank holder, andcmeans on said hollow piston rod for operatively connecting said outer blank holder to said second piston after said outer blank holder and said third piston have moved through a given distance.

3. A drawing press comprising a table, an outer annular. blank holder and an inner annular blank holder, both fitted to slide with respect to said table, a fixed drawing punch on said table, a matrix adapted to cooperate with said holders and said punch, a cylinder I disposed in a fixed position with respect to said table and having three com artments, a first piston mounted to slide in tlie first compartment, a piston rod on said piston, means operatively connecting said piston rod to said inner blank holder, a second piston mounted to slide in the second compartment, a hollow piston rod on said second piston which is Q mounted to slide on the piston rod of said first piston, a third piston arranged in the third compartment and mounted to slide on said hollow piston rod, means operatively connecting said third piston to said outer blank holder, and a check on said hollow piston rod which check is so positioned as to be engaged by said means for connecting said outer blank holder to said second piston only after said outer blank holder and said third piston have moved through a given distance.

4. A drawing press comprising a table, an outer annular blank holder and an inner annular blank holder, both fitted to slide with respect to said table, a fixed drawing punch on said table, a matrix adapted to cooperate with said holders and said punch, a cylinder disposed in a fixed position with respect to 7 said table and having two compartments, a

piston mounted to slide in the first compartment, a piston rod on said piston,vmeans ineluding a spring operatively connecting said piston rod to said inner blank holder, a piston mounted to slide in the second compartment and on said piston rod, and means operatively connecting said piston in the second compartment to said outer blank holder.

In testimony whereof I affix my signature.

OTTO KI'THNER. 

